Understand foliation differences, and investigate examples of slate, schist, and gneiss foliation. ... Is soapstone foliated or nonfoliated? Is sandstone ...What is one difference between the metamorphic rocks quartzite and hornfels? Hornfels is foliated, quartzite is nonfoliated. Hornfels contains plagioclase; quartzite does not contain plagioclase. Hornfels is produced by regional metamorphism, quartzite is produced by contact metamorphism. Hornfels is medium grained; quartzite is fine grained.Professional installation can raise the cost an additional $50 to $65 per square foot, bringing the total for professionally installed soapstone countertops to between $95 and $150 per square foot ...Exercise 7.2 Naming Metamorphic Rocks. Provide reasonable names for the following metamorphic rocks: A rock with visible minerals of mica and with small crystals of andalusite. The mica crystals are consistently parallel to one another. A very hard rock with a granular appearance and a glassy lustre.5/12/2019 Lab #7 (Metamorphic Rocks) All attempts used; correct answer displayed Soapstone is the only metamorphic rock that can be scratched by a fingernail. soapstone effervesces with application of dilute HCl, whereas hornfels does not. hornfels is foliated, whereas soapstone is unfoliated. hornfels effervesces with application of dilute HCl, whereas soapstone does not. soapstone is ... The result is a network of interlocking quartz grains of incredible power. Non-foliated metamorphic rocks do no longer have a platy or sheet-like shape. There are numerous ways that non-foliated rocks may be produced. Some rocks, including limestone are product of minerals that aren’t flat or elongate. 1. There are two different uses. If you are using double quotation marks for speech, as in a novel or other quotation, then, anything quoted within the quotation marks takes single quotes: "He yelled 'Stop talking' at me several times," said John. The BBC uses single quotation marks in headlines and its online site (inverted commas) but in ...Noun. (uncountable) A fine-grained homogeneous sedimentary rock composed of clay or volcanic ash which has been metamorphosed so that it cleaves easily into thin layers. (uncountable) The bluish-grey colour of most slate. (countable) A sheet of slate for writing on with chalk. (countable) A tile made of slate. (countable) A record of money owed.17 thg 5, 2023 ... Additionally, even rocks of a particular type may exhibit different properties depending on their mineralogical variations, thus potentially ...The difference between quartzite and gneiss is that View Available Hints) gneiss can be scratched by a fingernail, but quartzite cannot quartzite effervesces with application of dilute HCI, whereas gneiss does not the layers of quartzite are more flat than the layers of gneiss, which are noticeably wavy the layers of gneiss are more flat than the layers of quartzite, which are noticeably wavy ... However, most marble countertops are comparably priced or cheaper than soapstone. According to HomeAdvisor, soapstone slabs currently range between $55-$120 per square foot, with an average cost of $65 per square foot. Marble slabs can cost between $40-$100 per square foot but are around $60 per square foot on average.May 30, 2018 · Hornfels is a metamorphic rock formed when magma heats and recrystallizes the original rock. Pressure is not a factor in its formation. The name "hornfels" means "hornstone" in German, referring to the way the rock's texture and toughness resemble animal horn. The colors of hornfels are as variable as the source rock used to produce it. Expert Answer. Transcribed image text: The difference between hornfels and soapstone is that View Available Hint (s) O hornfels is foliated, whereas soapstone is unfoliated. O soapstone can be scratched by a fingernail, but hornfels cannot. The majority of rocks have a spotted appearance, like the hornfels in Figure 14.36. The spots are altered cordierite porphyroblasts. Figure 10.2 is a picture of a different biotite hornfels, and Figure 13.24 is a picture of a hornblende hornfels from near Wawa, Ontario. Both formed by contact metamorphism of a pelitic rock.It is a low-grade metamorphic rock that splits into thin pieces. Soapstone. metamorphic rock that consists primarily of talc with varying amounts of other minerals such as micas, chlorite, amphiboles, pyroxenes, and carbonates. It is a soft, dense, heat-resistant rock that has a high specific heat capacity.Name the coarse grained, foliated rock. Gneiss. Which metamorphic rock is composed of quartz? Quartzite. What process forms hornfels? Heat from nearby lava/magma. Which sedimentary rock is most likely changed to slate during regional metamorphism? Shale. Which physical characteristic best describes the rock phyllite?Hornfels is a fine-grained nonfoliated metamorphic rock with no specific composition. It is produced by contact metamorphism. Hornfels is a rock that was "baked" while near a heat source such as a magma chamber, sill, or dike. The specimen shown above is about two inches (five centimeters) across. Schist is a type of metamorphic rock characterized by its foliated texture, which means it possesses distinct layers or bands of minerals that have undergone significant physical and chemical changes due to heat, pressure, and other geological processes. The term “schist” is derived from the Greek word “schízein,” meaning “to …Type Metamorphic Rock Texture Non-foliated; Medium-grained Composition Quartz Index Minerals Color White to off-white Miscellaneous Interlocking grains Metamorphic Type Regional or Contact Metamorphic Grade Variable Parent Rock Quartz Sandstone Metamorphic Environment Variable grade regional or contact metamorphism along a …Skarn: pyroxene-garnet-carbonate hornfels Soapstone: chiefly talc Hornfels: any metamorphic rock with nondirectional structure Serpentine * Metaquartzite Marble Skarn: pyroxene-garnet-carbonate hornfels Graphite Marble Chlorite Marble Serpentine Marble (Ophicalcite) Hornfels: any metamorphic rock with nondirectional structure Serpentine * Medium orJun 24, 2019 · What is Soapstone? Soapstone, also known as steatite, is a natural quarried stone that is often used as a building material. The natural stone is comprised of mostly talc, while also containing other minerals such as chlorite and carbonates. Because of the high concentration of talc present in the stone, soapstone has a smooth surface. quartzite, hornfels, marble. Metamorphic index minerals are used by geologists to distinguish among different _____. zones of regional metamorphism. ... How is confining pressure different from differential stress? When a rock is under confining pressure, all of the forces are applied to the rock equally in all directions. However, pressure ...As nouns the difference between hornfels and basalt. is that hornfels is any of a series of contact metamorphic rocks that have been baked and indurated by the heat of intrusive …While you can’t seal a soapstone countertop, you can oil the stone, which helps protect it and ensure a uniform patina/darkening. Difference 5: Maintenance. Both soapstone and granite require care and maintenance. As mentioned, soapstone needs to be oiled from time to time. The first time you oil your soapstone counters will be the most ...As nouns the difference between dolomite and soapstone. is that dolomite is a saline evaporite consisting of a mixed calcium and magnesium carbonate, with the chemical formula CaMg (CO 3) 2; it also exists as the rock dolostone while soapstone is a soft rock, rich in talc, also containing serpentine and either magnetite, dolomite or calcite.Hornfels. Hornfels is a metamorphic rock formed by the contact between mudstone / shale, or other clay-rich rock, and a hot igneous body, and represents a heat-altered equivalent of the original rock. This process is termed contact metamorphism. Because pressure is not a factor in the formation of hornfels, it lacks the foliation seen in many ... It is a low-grade metamorphic rock that splits into thin pieces. Soapstone. metamorphic rock that consists primarily of talc with varying amounts of other minerals such as micas, chlorite, amphiboles, pyroxenes, and carbonates. It is a soft, dense, heat-resistant rock that has a high specific heat capacity. Some hornfels contain grains that become visible if a rock is weathered (because different minerals weather in different ways) but, because of the generally ...Another obvious difference between soapstone and quartz is grain pattern. Unlike veining, grain pattern is not a natural characteristic of the stone. Instead, it is caused by the manufacturing process. Grain pattern is the term used to describe the random pattern of veins in a pare of stone. When a stone is first mined, it is completely uniform.Scale bar: 1 mm. Left- An undeformed granitic rock containing the mica mineral biotite (Bt), plagioclase feldspar (Pl), potassium feldspar (Kfs), and quartz (Qtz). Right- A metamorphic rock (mylonite) resulting from extreme deformation of granitic rocks. Quartz crystals have been flattened and deformed. The other minerals have been crushed and ... As nouns the difference between metamorphic and hornfels is that metamorphic is (mineralogy) a rock that has been changed from its original form by subjection to heat and/or pressure while hornfels is any of a series of contact metamorphic rocks that have been baked and indurated by the heat of intrusive igneous masses and rendered massive, hard, splintery, and in some …Soapstone is much softer than other popular countertop materials, including granite, marble, and engineered quartz. Because of this, it has appeal for savvy DIY homeowners who have ambitions of fabricating their own kitchen surfaces. Unlike most other natural stones, soapstone is nonporous and does not need to be sealed. Untreated, …Soapstone: chiefly talc Hornfels: any metamorphic rock with nondirectional structure Serpentine * Metaquartzite Marble Skarn: pyroxene-garnet-carbonate hornfels The difference between hornfels and soapstone is that View Available Hint(s) O hornfels is foliated, whereas soapstone is unfoliated. O soapstone can be scratched by a fingernail, but horntels cannot. O soapstone is foliated, whereas hornfels is unfoliated. O the layers of soapstone are more flat than the layers of hornfels, which are ...Soapstone, also known as steatite, is a natural quarried stone that is often used as a building material. The natural stone is comprised of mostly talc, while also containing other minerals such as chlorite and carbonates. Because of the high concentration of talc present in the stone, soapstone has a smooth surface.Get detailed information about Hornfels vs Rhyolite texture, color, appearanceStudy with Quizlet and memorize flashcards containing terms like What is the difference between marble and quartzite? Quartzite is made from sandstone; marble is made from granite. Quartzite is made from shale; marble is made from granite. Quartzite is made from sandstone; marble is made from limestone. Quartzite is made totally of the mineral calcite; marble is made totally of the mineral ... The most common hornfels (the biotitehornfels) are dark-brown to black with a somewhat velvety lusterowing to the abundance of small crystalsof shining black mica. Also, most common hornfels have a black streak. The limehornfels are …Get to know more information about Hornfels and Soapstone origin and discoverer. Get to know more information about Hornfels and Soapstone origin and discoverer. Home. Igneous Rocks-Shonkinite. Basaltic Trachyandesite. Comendite. Fossil Rocks + Novaculite. Sandstone. Coal. Metamorphic Rocks + Schist. Marble. Quartzite.Aside from texture, the outstanding difference between the hornfels and microgranite assemblages is that the mafic mineral in latter is almost exclusively hornblende, whereas hornfels contains hedenbergite and fayalite but little or no hornblende. Therefore, the microgranite must have crystallized under a substantially greater a H2O. Rock ...d. contact metamorphism. a. confining pressure. We have an expert-written solution to this problem! Metamorphic rocks are classified primarily on. a. texture—the presence or absence of foliation. b. mineralogy—the presence or absence of quartz. c. environment of deposition. d. chemical composition. texture—the presence or absence of ...Soapstone (also known as steatite or soaprock) is a talc-schist, which is a type of metamorphic rock. It is composed largely of the magnesium rich mineral talc . It is produced by dynamothermal metamorphism and metasomatism , which occur in the zones where tectonic plates are subducted , changing rocks by heat and pressure, with influx of ...Hornfels. Hornfels is a metamorphic rock formed by the contact between mudstone / shale, or other clay-rich rock, and a hot igneous body, and represents a heat-altered equivalent of the original rock. This process is termed contact metamorphism. Because pressure is not a factor in the formation of hornfels, it lacks the foliation seen in many ... Check out Argillite vs Hornfels information. Home. Igneous Rocks-Shonkinite. Basaltic Trachyandesite. Comendite. Fossil Rocks + Novaculite. Sandstone. Coal. Metamorphic Rocks +The majority of rocks have a spotted appearance, like the hornfels in Figure 14.36. The spots are altered cordierite porphyroblasts. Figure 10.2 is a picture of a different biotite hornfels, and Figure 13.24 is a picture of a hornblende hornfels from near Wawa, Ontario. Both formed by contact metamorphism of a pelitic rock. 14/19 Correct In general, quartzite is one color, whereas gneiss has a striped, two-colored barcode appearance. Lab Activity 7.4.2 - The Differences between Igneous, Sedimentary, and Metamorphic Rocks By this point, you have studied igneous, sedimentary, and metamorphic rocks.Pyroxenite. Pyroxenite is an ultramafic igneous rock that contain pyroxene group minerals such as augite, diopside, hypersthene, bronzite or enstatite. This is a coarse-grained rock and that contains at least 90 percent pyroxene minerals. Also Pyroxenite contain olivine and oxide minerals, when it occurs in layered intrusions or nepheline.Hornfels is a fine-grained nonfoliated metamorphic rock with no specific composition. It is produced by contact metamorphism. Hornfels is a rock that was "baked" while near a heat source such as a magma chamber, sill, or dike. The specimen shown above is about two inches (five centimeters) across.The hardness of Soapstone is 1 and that of Hornfels is 2-3. The types of Soapstone are Not Available whereas types of Hornfels are Biotite hornfels. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Soapstone is black while that of Hornfels is unknown.Figure 6.5.1 6.5. 1: Pressure-temperature graph diagram showing metamorphic zones or facies. In the late 1800s, British geologist George Barrow mapped zones of index minerals in different metamorphic zones of an area that underwent regional metamorphism. Barrow outlined a progression of index minerals, named the Barrovian Sequence, that ...These are common around intrusive igneous bodies and are hard to identify. The protolith of hornfels can be even harder to distinguish, which can be anything ...Submit Part B - Differentiating between Hornfels and Soapstone The difference between hornfels and soapstone is that View Available Hint(s) the layers of soapstone are more flat than the layers of hornfels, which are noticeably wavy soapstone is foliated, whereas hornfels is unfoliated soapstone can be scratched by a fingernail, but hornfels ...The way rocks are formed determines which type of rocks they are. Explore the 3 classes, or types of rocks: igneous, metamorphic, and sedimentary.Crystals in hornfels grow smaller with metamorphism, and become so small that specialized study is required to identify them. These are common around intrusive igneous bodies and are hard to identify. The protolith of hornfels can be even harder to distinguish, which can be anything from mudstone to basalt. Figure 6.18: Macro view of quartzite.foliated. granite. looks like "squashed" granite. gneiss. any foliated metamorphic rock with compositional layering (alternating dark and light) blueschist. can be foliated or non-foliated. glaucophane, kyanite, lawsonite. really, really blue.The result is a network of interlocking quartz grains of incredible power. Non-foliated metamorphic rocks do no longer have a platy or sheet-like shape. There are numerous ways that non-foliated rocks may be produced. Some rocks, including limestone …Part C-Differentiating between Serpentinite and Chlorite Schist The difference between serpentinite and chlorite schist is that View Available Hints) chlorite schist effervesces with application of dilute HCl, whereas serpentinite does not chlorite schist can be scratched by a fingernail, but serpentinite cannot chlorite schistis foliated, whereas serpentinite is unfoliated serpentinite ...14 thg 5, 2015 ... Limestone can be found in the form of stalactites and stalagmites. This sedimentary rock is rich in calcium carbonate and can also be ...Hornfels. Lapis Lazuli. Marble. Mariposite. Novaculite. ... Soapstone. Soapstone is a talc ... Dacite - a light-colored extrusive igneous rock intermediate between ...Hornfels is a metamorphic rock formed by the contact between mudstone / shale, or other clay-rich rock, and a hot igneous body, and represents a heat-altered equivalent of the original rock. This process is termed contact …Pounamu is a word that describes stone that Māori, and many New Zealanders, consider has a spiritual significance. It is highly prized stone for its beauty, its hardness and for its value as a symbol of authority and status. Pounamu was also traditionally used to trade and to develop relationships.Scratch the surface of the stone with your fingernail. Soapstone is very soft; it is assigned a rating of 2 on the Mohs Hardness Scale. This means that simply by drawing your fingernail across the surface of the stone you should be able to mark it. Rub the stone. There should be a waxy, soapy feel to the surface of the stone, whether it is ...Get detailed information about Hornfels vs Soapstone texture, color, appearanceFigure 7.2.4 Examples of foliated metamorphic rocks: (A) Slate, (B) Phyllite, (C) Schist, (D) Gneiss. If a rock is buried to a great depth and encounters temperatures that are close to its melting point, it may partially melt. The resulting rock, which includes both metamorphosed and igneous material, is known as. migmatite. Soapstone (also known as steatite or soaprock) is a talc-schist, which is a type of metamorphic rock. It is composed largely of the magnesium rich mineral talc . It is produced by dynamothermal metamorphism and metasomatism , which occur in the zones where tectonic plates are subducted , changing rocks by heat and pressure, with influx of ... All soapstone is soft, between 1-4.5 mols, so yes it will scratch. Softer soapstones will scratch with a finger nail while the "harder" ones will take a key or knife to scratch. ... Quartz is a man-made material that comes in many different shades and patterns. Quartzite is a natural stone quarried from the earth. It is also one of the hardest ...Similarly, a gneiss that originated as basalt and is dominated by amphibole, is an amphibole gneiss or, more accurately, an amphibolite. Figure 7.2.4 7.2. 4 Examples of foliated metamorphic rocks: (A) Slate, (B) Phyllite, (C) Schist, (D) Gneiss. If a rock is buried to a great depth and encounters temperatures that are close to its melting point ...Pounamu is a word that describes stone that Māori, and many New Zealanders, consider has a spiritual significance. It is highly prized stone for its beauty, its hardness and for its value as a symbol of authority and status. Pounamu was also traditionally used to trade and to develop relationships.Mineral grains are oriented parallel to the direction of the weakest stress applied. The figure below shows a metaconglomerate. Place the thick arrows in the direction of maximum stress and the thin arrows in the direction of minimum stress. If stress from all directions is equal, place all thin arrows. Drag the appropriate labels to their ...Study with Quizlet and memorize flashcards containing terms like According to this metamorphic facies graph, which of the following statements is TRUE? A. Blueschist facies rocks form at high pressures and low temperatures. B. Hornfels facies rocks form in a narrow range of temperature conditions (<400°C). C. Greenschist facies form at depths greater than 35 km. D. The highest pressure facies ...Hornfels. Hornfels is a fine-textured metamorphic rock formed by contact metamorphism.Contact metamorphism occurs when a mass of hot magma intrudes into preexisting rock, whether by injecting itself into a crack or by ascending in a large body (e.g., pluton).Rock in close proximity to the magma is temporarily softened or melted and …A metamorphic facies is a set of mineral assemblages in metamorphic rocks formed under similar pressures and temperatures. The assemblage is typical of what is formed in conditions corresponding to an area on the two dimensional graph of temperature vs. pressure (See diagram in Figure 1). Rocks which contain certain minerals can therefore …Argillite. "Argillite" may also refer to Argillite, Kentucky. Grey chunks of graptolitic argillite on Pakri Peninsula, Estonia; yellowish and white chunks are limestone. Argillite ( / ˈɑːrdʒɪlaɪt /) is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillaceous rocks are basically lithified muds and oozes.Metamorphic rock, deformed during the Variscan orogeny, at Vall de Cardós, Lérida, Spain. Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than 150 to 200 °C (300 to 400 °F) and, often, elevated pressure ... Mar 11, 2023 · Why is soapstone called soapstone? Soapstone is the common name for the mineral steatite. Steatite is at least 50% talc combined with other minerals, mostly magnesite, that have been geologically metamorphosed into stone through a combination of heat, pressure and time. It is called soapstone because the talc gives the stone a soapy feel. The main difference between these rocks is that metamorphic rocks are formed from already existing rocks. Sedimentary and igneous rocks, on the other hand, are formed into rocks by another material. ... Non-foliated rocks include rocks like quartzite, hornfels, marble, or soapstone. You May Also Like: Types Of Landforms: From The …Phyllite is a foliated metamorphic rock rich in tiny sheets of sericite mica. It presents gradation in degree of metamorphism ranging between slate and mica schist. The color varies between black and gray to greenish-gray (Fig. 7.11 ). The phyllite forms from pelitic sediments (shale and mudstone) at a slightly higher degree of regional ...[1] In industrial applications soapstone refers to dimension stone that consists of either amphibole-chlorite-carbonate-talc rock, talc-carbonate rock, or simply talc rock and is sold in the form of sawed slabs. "Ground soapstone" sometimes …Study with Quizlet and memorize flashcards containing terms like What is the difference between marble and quartzite? Quartzite is made from sandstone; marble is made from granite. Quartzite is made from shale; marble is made from granite. Quartzite is made from sandstone; marble is made from limestone. Quartzite is made totally of the mineral calcite; marble is made totally of the mineral ...[1] In industrial applications soapstone refers to dimension stone that consists of either amphibole-chlorite-carbonate-talc rock, talc-carbonate rock, or simply talc rock and is sold in the form of sawed slabs. "Ground soapstone" sometimes …Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas, Soapstone is available in black, black to grey, green, grey colors. Appearance of Hornfels is Dull and that of Soapstone is Dull, Banded and Foilated. Properties of rock is another aspect for Hornfels vs Soapstone. Normal soap stones last till either a boss is killed (any zone boss will do) or you/the host dies. The reward for using a normal soap stone is 25% of the souls a boss normally drops (only exception is random encounter pursuers which award 17k), a free body form, and a token of fidelity which is a comsumable that allows you to heal the host …2 minutes. 1 pt. Metamorphic rocks result from the. erosion of rocks. recrystallization of rocks. cooling and solidification of molten magma. compression and cementation of soil particles. Multiple Choice. Edit.It may be schistose or massive. Soapstone is formed by metamorphism of ultramafic protoliths (eg dunite or serpentinite) and metasomatism of siliceous dolomites. By mass, “pure” steatite is roughly 63.37% silica, 31.88% magnesia, and 4.74% water. It commonly contains minor quantities of other oxides such as CaO or Al2O3. Soapstone FormationSoapstone slabs cost $70 to $120 per square foot on average, according to Caesarstone. By comparison, Danby marble counters cost around $75 to $90 per square foot. Soapstone that has a higher talc ...Amazing Facts About Soapstone That You Must Know. Soapstone is a majestic metamorphic rock composed of talc minerals with a salient percentage of magnesium silicate. Its composition makes it a suitable stone for various industries due to the presence of different minerals. Cosmetics, sculpture, construction, and soap & …Between 1979 and 1984, the Geological Survey of Finland carried out detailed investigations at Kontiolahti, Joensuu where andalusite and kyanite (Fig. 9.5.8) occur together in the lower Jatulian Hokkalampi paleosol (Marmo, 1988).The total mineral reserves of the six mineralized zones that were evaluated contain at least 25 Mt of rock averaging …1 Definition. 1.1 Definition. Rhyolite is a fine-grained igneous rock which is rich in silica. Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat …Figure 7.2.4 Examples of foliated metamorphic rocks: (A) Slate, (B) Phyllite, (C) Schist, (D) Gneiss. If a rock is buried to a great depth and encounters temperatures that are close to its melting point, it may partially melt. The resulting rock, which includes both metamorphosed and igneous material, is known as. migmatite.There are two basic types of metamorphic rocks. Foliated metamorphic rocks have a layered or banded appearance that is produced by exposure to heat and directed pressure. Examples of foliated rocks include: gneiss, phyllite, schist, and slate. Non-foliated metamorphic rocks do not have a layered or banded appearance.Which rock? Rocks are made of minerals. Different minerals have different properties, with some minerals being significantly harder, more dense, or tougher than ...Hornfels is a metamorphic rock formed when magma heats and recrystallizes the original rock. Pressure is not a factor, The streak of Hornfels is unknown while that of Basalt is white to grey. The spec, Soapstone mineral specimens collected from Otta, central Norway. Composed p, Soapstone – Soapstone (also known as steatite, or soaprock) is a talc-schist w, The streak of Hornfels is unknown while that of Basalt is white to grey. The specific heat capacity of Hornfels is 0., A mortar and pestle is about as lo-fi as it gets, a literally ancient implement comprised of a stu, Table 6.1: Metamorphic rock identification table. 6.2.1 Foliation and Lineation. Foliation is a term used that des, Why is soapstone called soapstone? Soapstone is the common nam, The differences between hornfels and soapstone are tha, foliated. granite. looks like "squashed" gran, Phyllite Rock. Phyllite is a foliated metamorphic rock that is p, Oct 27, 2021 · These conditions often stretch, twist and fold, Phyllite is a foliated metamorphic rock that has been subjected to low, Figure 7.2.4 Examples of foliated metamorphic rocks: (, What is the difference between hornfels and soapstone? O, 25 thg 1, 2021 ... ... soapstone more of a family of stones. Why We, Hornfels is a metamorphic rock formed by the contact between mu, Argillite. "Argillite" may also refer to Argillit.